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mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.onmicrosoft.com; s=selector2-citrix-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=vnW0b30z1hZxcDTtu+jo26HtPh1/6e5wL35MPxOOP64=; b=M+kIdi67rmWsPY9EpG7swpy6PloOr5Di2owF1+0buHT1NOcSz6xVWZVoYZApJQ5ONapKv0SQ2tdjSjkX6QmTh4mwbYBXAJDyWGn0cYqdCaJ3d/O1acOXOwF2LrM9IASFbWuF8ouxhBZB0L2cw/NRIfch6jqPQq4E000RdwsLxlM= Subject: Re: [PATCH 06/10] stubdom/xenstored: Fix uninitialised variables in lu_read_state() To: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , Xen-devel CC: Ian Jackson , Wei Liu References: <20210212153953.4582-1-andrew.cooper3@citrix.com> <20210212153953.4582-7-andrew.cooper3@citrix.com> From: Andrew Cooper Message-ID: <226c35c2-2280-8353-74d0-cc35e7f84de6@citrix.com> Date: Fri, 12 Feb 2021 17:01:25 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; 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X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?RTc1cnorT1ZzQTJyb1NrbVNBR3dTVXZxUnJacnorbXJhZC9oQmM1THIrU0cz?= =?utf-8?B?cGI2YmhydWtMUE5xdGdINGVYZFplMEZlbEZsUVloNS9iTzBTcUorRVVtVTVZ?= =?utf-8?B?cGlVdFNaWGZIOEdUd1R4VjZZVFRtMVFCdm5GeU9oSHphUUpnTnVVMFkweisx?= =?utf-8?B?QVFZK0tFMmsyYkplUmRKcWNEcDZVaGJObGhLSEhaMWhtWnFjcnZMMlBHVFRG?= =?utf-8?B?b3hEVkY2d2p4V3BNUjk4dXdWV0RzVFpXZ21LWk9hRGowYzBoZ1c1NTArQ2tL?= =?utf-8?B?SlROdm5MK3VFWTVjOXFqdEY1c3hNY2x3aTRPeVZoQ3JKMlZ3SmNWSGo1UHF1?= =?utf-8?B?OXJxWVZQaTh6Z1c0OW9kY1AxSEhZL0tzOE5OMDhTMTFBR3VsdzZFTzJxbU9a?= =?utf-8?B?MVBLMlZ4Ui84OWdFTmUwQWpIQXhJcDF2c2cxWElLcVcrK0VGNitJamxNdUk1?= =?utf-8?B?RzRwU1V1cFlVaDNGMS9VcTRyZkRCQjFRQ3FZdjJ2STliOXdIaGRKanBpTVlX?= =?utf-8?B?TWZzNEhQVW5ZdncrYzNpU1BoVmlqS0MvME9wWlRYWVZpMHFUR05oaVJSekdk?= =?utf-8?B?R0kxVjhweUFZcFh0UU44SnlmRURJbmZvY2xtcTNoY3RXUEFRcVFvUi9vNTBL?= =?utf-8?B?NjllVktWdGRvNVlVUUNFYTh6K2RVVG1pbmQ0L2kvUmFLSHFadWJmTW1ET1Js?= =?utf-8?B?bXZKMi9LNTBYR0FScHIwaWR5aXFWa2pPRzBFMVZWekNYWm11M0s4bTEvM211?= =?utf-8?B?Tk05WWRKSGpOMndqT0hvei9raE9ycVFQdlNtUUptM3gwYWg4ZFBiWHVDVm1j?= =?utf-8?B?Ym1VVjg5RDVQNTlhVkRhSjhyZDhOdk51UTd5ckZucGd6L0x3a2N1Kys4ZlJH?= =?utf-8?B?a1h2K3U2ZkxvT0ZXTVFmNHRVdDFMd0dPd0Z0K3V4YlByYjNGV3A3KzVJR05P?= =?utf-8?B?YnM5WWU1WHM4UFAxVk01d3ZobUdJeDJEK05LSjFZdU1KeURsa3FHcUpOMXox?= =?utf-8?B?d29GOHZ6SUxKZXdFRUZzSHdRcktkaHhvaExVUm9iVG80cTVDOFoyZitReUtp?= =?utf-8?B?ZXR6Ry9OSVFBbUxGY1Y1NXdOTWdzT3hrZTN1MnlXcmRBQ3gwY0VWL1ZBVnlj?= =?utf-8?B?QW0yWHJ5VkR2VXhFVHdMdlVIWDBHS1lIdkoyQ2FoNGZYQlk1K1JoKzB2NnUr?= =?utf-8?B?NytINnZWSUZaVnZ6aUJ6V0VxSnhPbWJHaVoyakhpcmRLQWZpTUEzTUI3V1dy?= =?utf-8?B?OXBEYkc5eFhTODZyMGxtZHlRekxMUktsVHhwRWE2RkNBMDZoclN3a1AwYjFu?= =?utf-8?B?S2grdm1SYnVRNUdjYlVtYlhVcDZVLzlTNDNnTW1ub0c2YnAzcXk5cWZlNWF3?= =?utf-8?B?ZTlmMG9UYTFmNmpUcTA2Z3RzZGs1T1ZxL3VPNnM0dFdiQmV1MXlLOGVNcVk3?= =?utf-8?B?OHRuUjZDTXNFYmN2RStzMldLeDZ3RHNsWnNpeTVNMzcxWTgxVWVNaDZXalla?= =?utf-8?B?NUgxOTZ0T2thbThGd3ZvdzZXWWkwcEpYM043bktQbXZRYjEyalVaRzhqTEtQ?= =?utf-8?B?R1YrZDVWa1F5VEtyYVhLOFNteHJyMFlMcEcwcklENVdpQk0wT0dKQ3VTdjJB?= =?utf-8?B?OUFGMStyY053NVF1OFZoaHJpazI2N0tvR3dXMVlIajRKQUV2Y1VmeHlBVk1W?= =?utf-8?B?YjdwT0pSbmt2cTQyUTBPN1JCb2QwQ3g1VXpYMVJSUllnRVQvK29zYlZEVVlT?= =?utf-8?Q?tIgds9XvkaL0f09HIp4OUfXdCAK32RV1e4cRCXn?= X-MS-Exchange-CrossTenant-Network-Message-Id: 4aba431c-4dc5-488d-2972-08d8cf77d87b X-MS-Exchange-CrossTenant-AuthSource: BYAPR03MB3623.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Feb 2021 17:01:31.6031 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: pPqF5w9KQqHx1myJvmhftdpQFEvCBMji1ptm1fvTpjcMZesscGKBHskYgrQpzWP42u5nrQxg0zB3peCgGGKoF4xuQVl5QlzeR+T+Bitb2xw= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR03MB5348 X-OriginatorOrg: citrix.com On 12/02/2021 16:08, Jürgen Groß wrote: > On 12.02.21 16:39, Andrew Cooper wrote: >> Various version of gcc, when compiling with -Og, complain: >> >>    xenstored_control.c: In function ‘lu_read_state’: >>    xenstored_control.c:540:11: error: ‘state.size’ is used >> uninitialized in this >>    function [-Werror=uninitialized] >>      if (state.size == 0) >>          ~~~~~^~~~~ >>    xenstored_control.c:543:6: error: ‘state.buf’ may be used >> uninitialized in >>    this function [-Werror=maybe-uninitialized] >>      pre = state.buf; >>      ~~~~^~~~~~~~~~~ >>    xenstored_control.c:550:23: error: ‘state.buf’ may be used >> uninitialized in >>    this function [-Werror=maybe-uninitialized] >>       (void *)head - state.buf < state.size; >>                      ~~~~~^~~~ >>    xenstored_control.c:550:35: error: ‘state.size’ may be used >> uninitialized in >>    this function [-Werror=maybe-uninitialized] >>       (void *)head - state.buf < state.size; >>                                  ~~~~~^~~~~ >> >> Interestingly, this is only in the stubdom build.  I can't identify any >> relevant differences vs the regular tools build. > > But me. :-) > > lu_get_dump_state() is empty for the stubdom case (this will change when > LU is implemented for stubdom, too). In the daemon case this function is > setting all the fields which are relevant. So I spotted that.  This instance of lu_read_state() is already within the ifdefary, so doesn't get to see the empty stub (I think). Also, I'd expect the compiler to complain at -O2 if it spotted that code. > >> >> Signed-off-by: Andrew Cooper > > Reviewed-by: Juergen Gross Thanks, ~Andrew